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<title>Log Activity Diagram (H+,CO2)</title>
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<p>Example of a <b>log activity diagram</b> showing the <a href="SP_Activity.htm">activities</a>
(on a logarithmic scale) for all species in the system <nobr>H<sup>+</sup>,</nobr>
<nobr>CO<sub>2</sub>(g).</nobr> Note that the component
<nobr>CO<sub>3</sub><sup>2&#8722;</sup></nobr> in DATABASE has been
<a href="S_Modify_Chem_System.htm">exchanged for a reaction</a>,
in this case for <nobr>CO<sub>2</sub>(g).</nobr></p>

<p><center>
<img src="images/Diagr_LogaCO2.gif" border="1" alt="Diagram H+ / CO2" title="Diagram H+ / CO2" height="218" width="298">
</center></p>

<p>Note that for gases the <i>fugacity</i> <nobr>(&#8776;</nobr> partial pressure)
is calculated and it is displayed. The calculations consider the aqueous phase only,
and the concentrations for gases are set to zero and they are not displayed in
a <a href="S_Diagr_Log_CO2.htm">logarithmic diagram</a>.</p>

<p><b>Note:</b> &#147;log activity diagrams&#148; can only be created with the
<i>advanced</i> program level selected in the menu &#147;Preferences / <nobr>General
options&#148;</nobr> in SPANA.</p>

<p>The diagram displayed above was obtained with the following input file:</p>
<pre><code>2 4 0 0
H+, CO2(g)
OH-,   -14.0   -1 0
H2CO3,  -1.468  0 1
HCO3-,  -7.82  -1 1
CO3 2-,-18.149 -2 1
LAC, -9 0 H+
LAV, -3 -9.7  LA, -3.5</code></pre>

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